Typing speed and rhythm indicating apparatus for typewriters



Sept. 13, 1955 J BROOKS 2,717,688

TYPING SPEED AND RHYTHM INDICATING APPARATUS FOR TYPEWRITERS Filed Nov. 1, 1954 INVENTOR. 75 James Adm/7 fi/wka BY A 1? 3. w lg 4/ /@r ATTOENEK United States Patent TYPING SPEED AND RHYTHM INDICATING APPARATUS FOR TYPEWRITERS James Aaron Brooks, Prairie Village, Kans.

Application November 1, 1954, Serial No. 465,837

Claims. (Cl. 197-=187) This invention relates to indicators for use with typewriters and, more particularly, to apparatus for use in conjunction with a typewriter for indicating the speed and rhythm at which the typewriter is being operated by a typist.

The principal object of this invention is to provide apparatus for indicating when the speed at which a typewriter is being operated exceeds a predetermined figure and to further indicate whether or not the typist is operating the typewriter with the proper rhythm.

Another important object of the invention is to provide such apparatus which may be installed for use upon a typewriter without modification of the latter.

Another important object of the invention is to provide such apparatus which is adapted for giving speed and rhythm indications with respect to a number of preselected different speed settings.

Other more minor objects of this invention, including certain details of construction, the simplicity of the apparatus rendering it foolproof in operation and inexpensive to manufacture, and the like will be made clear or become apparent as the following specification progresses.

In the drawings:

Figure l is a composite view, partially in perspective, partially in elevation, and partially in section, showing the external appearance of the control, indicating and housing portion of this invention, certain portions of a typewriter with which this invention might be used, and the circuit breaker forming a part of this invention in its installed position with respect to fragments of such typewriter.

Fig. 2 is a sectional view taken on line IIII of Fig. l and showing a portion of the structure in elevation; and

Fig. 3 is a schematic diagram of the electrical circuit employed in one embodiment of this invention.

Referring first to Fig. 1, the numeral designates an operating lever of one form of conventional typewriter, lever 10 being pivoted as at 12 and provided with a depressible key 14 for manipulation by a typist using the typewriter to type a particular character. Obviously, the typewriter is conventionally provided with a number of levers 10 for the different characters of the alphabet.

Each lever 10 is operably coupled with an arm 16 pivoted as at 18 and provided with a type face 20 by means of a linkage 22, a pivoted arm 24, a linkage 26, a pivoted arm 28 and a linkage 30. Operably coupled with each arm 28, and thereby also with each lever 10, is a rearwardly extending rod 32 having a hooked portion 34 at the end thereof remote from arm 28.

The typewriter conventionally also includes a member 36 swingably mounted within the typewriter in a manner not shown for swinging movement of the lowermost end of member 36 toward and away from arm 28; member 36 forms a part of the spacing mechanism (otherwise not shown) forming a part of all conventional typewriters. The member 36 shown, and a similar member 2,717,688 Patented Sept. 13, 1955 not shown at the opposite side of the typewriter are interconnected by a rod 37 passing therethrough and extending transversely of the typewriter. Member 36 is provided with a laterally extending flange 39.

A lever 38, also pivoted as at 12, is provided with a spacing bar or key 40 for manipulation by a typist using the typewriter, and with an upstanding angular extension 42. Extension 42 is connected by a rod 44 having a hooked portion 46 at the end thereof remote from extension 42 with an element 48 extending transversely of the typewriter and forming a part of the spacing mechanism thereof.

The typewriter is also conventionally provided, internally of the outer housing thereof, with bracing and supporting structure such as a touch control adjustment bar 50 illustrated in Fig. 1. All of the structure heretofore referred to forms a part of the typewriter in conjunction with which the apparatus of this invention is to be employed.

A normally open, quick acting, single pole, single throw switch or circuit breaker 52, which preferably may be of the type available on the market under the trade name Microswitch, is mounted in any suitable fashion upon the structure or bar 50 as by a clamping plate 54 and fastening means 56. Switch 52 is coupled with the remainder of the apparatus of this invention by a 2-conductor, extension cable 58. Switch 52 is provided with a movable contact arm 53 and is modified by the addition of a forwardly extending element 55 having a hooked portion 57, element 55 being secured to arm 53 in any suitable fashion as by a rivet 5?. As will be clear from Fig. 1, switch 52 is so disposed within the typewriter upon structure 50 thereof that arm 53 will be actuated to close switch 52 each time flange 39 is swung forwardly by the pulling action of rod 32 exerted upon rod 37 when a lever 10 is operated by depression of a key 14. Similarly, arm 53 is moved to close switch 52 each time lever 38 is operated by depression of bar 49 by virtue of rod 44 pulling element 48 forwardly to engage hooked portion 57 of element 55.

Except for switch 52 and cable 58, the apparatus of this invention may be conveniently contained in a housing 60 upon which are mounted a pair of indicator bulbs 62 and 64 hereinafter to be more fully described, a speed indicating dial 66, a speed adjustment knob 68, and a power switch control knob 70. Emanating from housing 60, besides cable 58, is a power cord 72 provided with a plug '74 adapted for connection with a suitable source of alternating current power not shown.

Referring now to the schematic circuit diagram of Fig. 3, plug 74, which is adapted for coupling with a source of alternating current line voltage, is grounded as at 76 and is coupled with a power switch 78 by a conductor 80, conductors 76 and 80 being connected with the terminals of plug 74. Power from switch 78 is coupled by conductors 82 and 84 with a rectifying and filtering power supply comprising a selenium rectifier 86, a series impedance or resistance 88, a pair of grounded filtering capacitors and 92 and a grounded bleeder resistance 94 coupled in conventional manner to present a direct current potential output at terminal 96.

Power from switch 78 is also connected by conductors 82, 98 and 109 with a grounded primary winding 102 of a step-down, filament supply transformer 104 having a secondary winding 166. Power from switch 78, when the latter is closed, is likewise connected by conductors 82, 98 and 108 with a movable contactor arm 110 of a single pole, double-throw relay switch generally designated by the numeral 112 and having, besides contactor arm 110, a coil 114 and a pair of spaced contacts 116 and 118 adapted for alternate engagement by contactor arm 110. Contactor arm 110 is normally closed with contact 116 when coil 114 is deenergized and, upon energization of coil 114, arm 110 is swung into contacting engagement with contact 118.

Direct current potential supply terminal 96 is coupled through conductors 120, 122, a current limiting resistor 124 and conductor 126 with a coil 128 of a relay switch generally designated 130, and having, besides coil 128, a movable contactor arm 132 and a stationary contact 134 adapted to be contactingly engaged by arm 13?. whenever coil 128 is energized.

The circuit from terminal 96 through coil 123 proceeds from the latter by conductor 136, female plug 138, male plug 140 and conductor 142 of cable to normally open switch 52 hereinbefore described, thence continuing from switch 52 through conductor 144 of cable 53, male plug 140, female plug 138 and conductor 146 to the com mon ground. It will be noted that a discharge capacitance 148 is provided for coil 12S and coupled in parallel with the latter by conductors 150 and 152.

A vacuum tube 154 provided with a filament 156. a cathode 158, a control grid 160 and an anode or plate 162, has its filament 156 coupled with the secondary winding 106 by conductors 164 and 166 and its cathode coupled with the common ground through conductor 163 and a grounded cathode biasing resistance 169 by conductor 168.

With reference to the control grid circuit of tube 154, terminal 96 is coupled by conductors 120, 122 and 170 with arm 132 of normally open relay switch 130, contact 134 of switch 130 being in turn coupled by conductor 172, voltage dropping resistance 174 and conductor 176 with grid 160 of tube 154. A capacitance 173 is grounded as at 130 and is coupled with grid by conductors 182 and 176. An adjustably variable resistance 184 is grounded as at 186 and coupled by conductors 18S and 176 with control grid 160 of tube 154. it will be noted that capacitor 178 and resistance present a resistance-capacitance timing network of adjustably variable charge and discharge time constants, the resistance of series resistor 174 also having some effect upon the time constants involved.

Referring now to the plate circuit of tube 154, terminal 96 is coupled through conductors 120 and 190 with coil 114 of relay 112, and thence with plate or anode 162 by a conductor 192.

Glow discharge bulbs 62 and 64, which may preferably be neon-type bulbs such as those available on the market from various manufacturers under the designation NE-51, are respectively coupled with the common ground as at 194 and 196. Bulb 62 is also coupled with contact 116 of relay switch 112 by a conductor 198. while bulb 64 is similarly connected with contact 118 by a conductor 200.

Suitable values and specifications for certain of the components are as follows:

Switch 52, a V1 type Microswitch; relay 130, a 10,000 ohm relay having a coil 128 adapted to close contacts 132 and 134 whenever the current passing through coil 123 exceeds rnilliamperes; capacitance 148. a .05 microfarad capacitance; resistance 124, a 10,000 ohm resistor; resistance 174, a l-megohm resistor; capacitance 178, a .5 microfarad capacitance; resistance 184, a 500,000 ohm variable resistance; tube 154, a type 6AG5 vacuum tube; resistance 169, a 1,000 ohm resistance; relay 112, a 5,000 ohm relay having a coil 114 adapted to swing arm 110 out of contacting engagement with contact 116 and into contacting engagement with contact 118 when the current through coil 114 exceeds 8 milliamperes; bulbs 62 and 64, 110 volt neon bulbs; rectifier 86, a milliatnpere sclenium rectifier; resistance 88, a ohm resistor; capacitors 90 and 92, 20 microfarad filtering capacitors; resistance 94, a 25,000 ohm resistor; and transformer 104, a line to 6.3 volts step-down transformer.

In operation, plug 74 is placed in connection with a suitable alternating current line outlet and switch 70 is closed by the operator. Upon closure of switch 78 the alternating current line voltage is applied across indicator bulb 62 through the circuit traceable as follows:

From plug 74, through conductor 80, closed switch 70, conductors 82, 98 and 108, closed contacts and 116 of relay switch 112, conductor 198, bulb 62, conductor 194, the common ground, and conductor 76 bacl; to plug 74.

Simultaneously, upon closure of switch 78, power is supplied to primary 102 of transformer 104, and power from the secondary 106 of transformer 104 thereupon passes through filament 156 of tube 154 to heat cathode 158 of tube 154 for operation in its normal fashion. Also, upon closing of switch 78, power is supplied to the rectifier 86 and the filter 389092 to present a positive, direct current potential at terminal 96.

The value of the cathode biasing resistance 169 is so chosen with respect to the particular type of vacuum tube 154 being used that tube 154 will be normally cut-off or non-conducting in the absence of a positive input upon its control grid 160. The required positive potential for plate 162 of tube 154 is supplied from terminal 96 of the power supply through conductors and 190, coil 114 of relay 112 and conductor 192.

Since tube 154 is normally in cut-off or non-conducting condition, no current will flow through coil 114 in the absence of a positive potential signal upon control grid 160, and coil 114 will, therefore, not be energizes upon initial closure of switch 78 to change the position of contacting arm 110 from its disposition in initial cn gagement with contact 116 of relay 112. The direct current potential from terminal 96 is also made available at the contactor arm 132 of relay through conductor; 120, 122 and 170.

Additionally, upon initial closure of the power switch 78, a direct current potential is presented at normally open switch 52 installed on structure 50 of the typewriter through a circuit traceable as follows:

From terminal 96, through conductors 120 and 122, current limiting resistance 124, conductor 126, coil 128 of relay 130, conductor 136, plug 138140 and conductor 142 of cable 58.

Since switch 52 is normally open, no current will flow through the circuit just traced and particularly coil 128 upon initial closure of switch 78, contactor arm 132 thereby being left in its normally open disposition out of contacting engagement with contact 134.

Upon depression by the operator of the typewriter of any of the keys 14 or the bar 40, normally open switch 52 will be closed by virtue of the above-described mechanical intercoupling between levers 10 and 33 and switch 52. Upon closure of switch 52 current will be allowed to flow through coil 128 of relay 130 by means of the circuit previously traced from terminal 96 to switch 52, and thence through conductor 144 of cable 58, plugs 13$140 and conductor 146 to the common ground. Flow of current through coil 128 will cause contactor arm 132 of relay switch 130 to close into contacting engagement with contact 134, thereby coupling the direct current potential from terminal 96 with resistance 174, through the following circuit:

From terminal 96, through conductors 120 and 122, contacts 132 and 134 of switch 130, and conductor 172 to resistance 174.

Upon such potential being made available at resistance 174, current will fiow through the latter, part of such current continuing to ground through conductor 1S8, resistance 184 and conductor 186, and the remaining portion of such current acting to charge capacitor 178 in the manner well understood by those skilled in the art. Upon capacitor 178 becoming charged to a predetermined level, a direct current potential of predetermined value will be presented at conductor 176 and coupled with the control grid of tube 154. Upon imposition of such positive potential upon grid 160, tube 154.

will commence to conduct and current will flow through coil 114 of relay 112 by virtue of the following circuit:

From terminal 96, through conductors 120 and 190, coil 114, conductor 192, plate 162 of tube 154, through tube 154 to cathode 158 thereof and thence through conductor 168 and cathode resistance 169 to the common ground.

Upon such flow of current in the plate circuit of tube 154, and particularly through the coil 114 of relay 112, the contactor arm 110 of relay 112 will be swung out of contacting engagement with contact 116 and into contacting engagement with contact 118. When arm 110 is swung out of engagement with contact 116, bulb 62 obviously ceases to be lit. When contactor arm 110 is pulled into engagement with contact 118, the power circuit for bulb 64 is completed and bulb 64 is lit.

As soon as the operator ceases to depress the key 14 or the bar 40, switch 52 is opened, current ceases to flow through coil 128 of relay switch 130, switching contacts 132 and 134 of switch 130 are opened so that a direct current potential from terminal 96 is no longer supplied therethrough to resistance 174, and the charge built up on capacitor 178 gradually discharges through resistance 184 with consequent gradual falling of the potential presented at conductor 176 coupled with control grid 160 of tube 154. When the potential upon grid 160 has fallen below a predetermined level, tube 154 ceases to conduct, current ceases to flow through the plate circuit thereof, and coil 114 releases the contacting arm 110 for return to its normal position out of engagement with contact 118 and in contacting engagement with contact 116. Upon breaking the contact between arm 110 and 118, bulb 64 ceases to be lit; and upon arm 110 returning to contacting engagement with contact 116, bulb 62 is again lit.

It is significant to note that some little time is taken for capacitor 178 to discharge through resistance 184 after the switch 52 has been opened. Accordingly, tube 154 continues to conduct and bulb 64 remains lit for a moment after switch 52 has been opened. If switch 52 is again closed by depression of any of the keys 14 or the bar by the operator of the typewriter within an interval sufficiently short after the last depression of a key 14 or bar 40, current will again flow through coil 128 to close contacts 132 and 134, and to again supply the potential from terminal 96 for recharging capacitor 178 before it has fully discharged from the last previous depression of a key 14 or bar 40. If such successive depressions of keys 14 and bar 40 occur within a short interval predetermined by the values of capacitor 178 and resistance 184 (and to a limited extent by the value of resistance 174) the capacitance 178 will never be permitted to discharge below a point maintaining a certain predetermined potential upon grid 160 of tube 154.

In this situation, it is obvious that tube 154 will conduct continuously to maintain coil 114 energized and arm 1111 in engagement with contact 118, whereby bulb 64 remains continuously lit. Such is the condition when the operator of the typewriter is manipulating the keys 14 and bar 40 thereof at or in excess of a predetermined typing speed corresponding to the particular setting of adjustable resistance 184. In other words, when the typist is meeting or exceeding the typing speed corresponding to the setting of resistance 184, bulb 64 will remain continuously lit, providing that the rhythm with which the operator depresses keys 14 and bar 40 is of suiiicient uniformity that no interval between successive depressions occurs which permits the capacitor 178 to discharge below that predetermined level required for maintaining the grid 160 of tube 154 at that value of positive potential necessary for placing tube 154 in conducting condition.

If the operator is typing at a speed below that corresponding to the setting of resistance 184, bulb 64 will flicker on and off each time a key 14 or bar 40 is deall) pressed. Similarly, if the operator is typing above the speed corresponding to the setting of resistance 184, but occasionally depresses keys 14 or bar 40 out of that rhythm required for continuous conduction of tube 154, the bulb 64 will remain lit the majority of the time but will flick off and then back on each time an irregularity in rhythm occurs.

It will thus be apparent that bulb 64 is, in fact, the principal indicating device of the apparatus of this invention. For convenience and emphasis however, bulb 62 has additionally been provided in the preferred embodiment, the operation of bulb 62 being clear from the fact that it is energized each time bulb 64 is deenergized and vice versa. Thus, with the preferred embodiment illustrated, when the operator is typing at the required speed, bulb 64 will remain lit and bulb 62 will remain dark. When the operator drops below the required typing speed, bulbs 64 and 62 will flash on and off alternately. And, when the operator, although generally typing at the required speed, sulfers from nonuniformity of rhythm, the bulb 64 will be deenergized momentarily and bulb 62 will flash on to warn the operator of such fact.

The apparatus of this invention can be used to advantage by any one desiring to improve their typing tech nique. It serves both to furnish an indication of whether or not a predetermined typing speed is being met and also, to indicate whether or not the typist is maintaining the proper rhythm of operation necessary for correct typing at the predetermined speed.

Since the apparatus of this invention may normally be installed upon any conventional make of typewriter without modification of the latter by the provision of appropriate extension elements as at 55 and 57 on the contactor arm 53 of switch 52, and since the apparatus may obviously be manufactured at a relatively low cost, it is ideally suited for use in schools and the like for instructing students in the proper manner of operation of typewriters.

Obviously, many minor changes or modifications might be made in the apparatus of this invention without departing from the spirit of the invention. Accordingly, it is desired to be limited only by the scope of the appended claims.

Having thus described the invention What is claimed as new and desired to be secured by Letters Patent is:

1. The combination with a typewriter having a number of manually depressible, operating levers, of a typing speed and rhythm indicator comprising electrically responsive apparatus, including an indicating device which operates when said apparatus is supplied with electrical power of a predetermined magnitude; a control circuit for said apparatus coupled with the latter and adapted for coupling with a source of electrical power of magnitude greater than said predetermined magnitude; a normally open switch coupled in series with said control circuit; means operably coupling said normally open switch to complete said control circuit each time any one of said levers of said typewriter is depressed; and a capacitively reactive, impedance network having predetermined charge and discharge constants coupled with said control circuit.

2. The combination with a typewriter having a number of manually depressible, operating levers, of a typing speed and rhythm indicator comprising an electrically responsive indicating device; a power circuit for said device coupled with the latter and adapted for coupling with a source of electrical power; a normally close switch coupled in series with said power circuit; electrically responsive structure operably coupled with said switch for opening the latter whenever said structure is supplied with electrical power of a predetermined magnitude; a control circuit for said structure coupled with the latter and adapted for coupling with a source of electrical power of magnitude greater than said predetermined magnitude; a normally open switch coupled in series with said control circuit; means operably coupling said normally open switch to complete said control circuit each time any one of said levers of said typewriter is depressed; and a capacitively reactive, impedance network having predetermined charge and discharge constants coupled with said control circuit.

3. The combination with a typewriter having a number of manually depressible, operating levers, of a typing speed and rhythm indicator comprising an electrically responsive indicating device; a power circuit for said device coupled with the latter and adapted for coupling with a source of electrical power; a normally closed switch coupled in series with said power circuit; an electrically responsive mechanism operably coupled with said switch for opening the latter whenever said mechanism is supplied with electrical power; an operating circuit for said mechanism coupled with the latter and adapted for coupling with a source of electrical power; an electrically responsive, normally open, electronic switching unit coupled in series with said operating circuit, said unit being responsive to direct current, electrical power of a predetermined magnitude for closing said unit to complete said operating circuit; a control circuit for said unit coupled with the latter and adapted for coupling with a source of direct current, electrical power of magnitude greater than said predetermined magnitude; a normally open switch coupled in series with said control circuit; means operably coupling said normally open switch with said typewriter for closing said normally open switch to complete said control circuit each time any one of said levers of said typewriter is depressed; and a capacitively reactive, impedance network having predetermined charge and discharge constants coupled with said control circuit.

4. A typing speed and rhythm indicator for use with a typewriter having a number of manually depressible, operating levers, said indicator comprising an electrically responsive indicating device; a power circuit for said device coupled with the latter and adapted for coupling with a source of electrical power; a normally closed switch coupled in series with said power circuit; an electrically responsive mechanism operably coupled with said switch for opening the latter whenever said mechanism is supplied with electrical power; an operating circuit for said mechanism coupled with the latter and adapted for coupling with a source of electrical power; an electrically responsive, normally open, electronic switching unit coupled in series with said operating circuit, said unit being responsive to direct current, electrical power of a predetermined magnitude for closing said unit to complete said operating circuit; a control circuit for said unit coupled with the latter and adapted for coupling with a source of direct current, electrical power of magnitude greater than said predetermined magnitude; a normally open switch coupled in series with said control circuit; a resistance-capacitance network having predetermined charge and discharge constants coupled with said control circuit; an electrically responsive assembly operably coupled with said normally open switch for closing the latter whenever said assembly is supplied with electrical power; an actuating circuit for said assembly coupled with the latter and adapted for coupling with a source of electrical power; and a normally open circuit breaker coupled in series with said actuating circuit and adapted for being mounted on said typewriter for closing of said circuit breaker to complete said actuating cir' cuit each time any one of said levers of said typewriter is depressed.

5. A typing speed and rhythm indicator for use with a typewriter having a number of manually depressible, operating levers, said indicator comprising an electrical, glow discharge bulb; a power circuit for said bulb coupled with the latter and adapted for coupling with a source of electrical power; a vacuum tube having an anode, a control grid and a cathode; an anode circuit adapted for coupling the anode and the cathode of said tube with a source of direct current, electrical power; a grid circuit adapted for coupling the grid and the cathode of said tube with a source of direct current, electrical power; a signaling circuit adapted for coupling with a source of electrical power; a normally open circuit breaker coupled in series with said signaling circuit and adapted for being mounted on said typewriter for closing of said circuit breaker to complete said signaling circuit each time any one of said levers of said typewriter is depressed; a first relay having a coil coupled in series with said signaling circuit and a pair of normally open switch contacts coupled in series with said grid circuit; a resistance-capacitance network having predetermined charge and discharge time constants coupled with said grid circuit; and a second relay having a coil coupled in series with siad plate circuit and a pair of normally closed switch contacts coupled in series with said power circuit.

References Cited in the tile of this patent UNITED STATES PATENTS 2,074,051 Fitch Mar. 16, 1937 2,348,744 McMurry May 16, 1944 2,665,792 Strauss Jan. 12, 1954 

